Endothelium-derived nitric oxide (NO) synthesized from L-arginine by endothelial nitric oxide synthase (eNOS) encoded by the NOS3 gene. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis of NOS3 identifies G to T substitution at 984 position of exon 7 which changes Glu to Asp amino acid at codon 298. We have done casecontrol association study to investigate the relationship between Glu298Asp variant and coronary artery disease (CAD) of North Indian origin. The study consists of 199 unrelated patients with positive history of coronary artery disease and 153 unrelated healthy individuals without having history of CAD. Though we did not find any significant association of eNOS gene polymorphism with coronary artery disease (p=0.077), a stepwise increase in frequency of T allele of eNOS gene with the severity in terms of number of vessels involved was observed (T allele in one, two and three vessel; 10.2%, 14.5% and 16.4% respectively). Presence of diabetes, hypertension, smoking, elevated level of triglycerides and reduced level of HDL cholesterol were found as significant predictors of coronary artery disease on multivariable logistic regression analysis. A larger sample size study is needed to evaluate the association of eNOS polymorphism and CAD.
